The apparatus of the present invention is used to support and seal around a pipe or other string within a wellhead.
An example of a prior structure is illustrated in U.S. Pat. No. 2,920,909 to H. Allen. In this patent the pipe is supported by slips within a slip bowl which is supported on the tapered interior of the wellhead housing and upper slips are supported above a conical shaped seal ring so that the load of the supported pipe causes the seal ring to expand inward and outward into sealing engagement between the exterior of the pipe and the interior of the wellhead housing.
U.S. Pat. Nos. 3,311,168 and 4,390,186 disclose similar structure in which a landing ring supports inner and outer seal rings and the slip bowl engages the seal rings so that the pipe load of the slip bowl is transmitted at least in part through the seal rings.
U.S. Pat. No. 4,494,778 to C.W. Johnson discloses another similar structure in which the slip bowl is connected to a seal assembly ring above the slip bowl by cap screws so that the seal assembly is moved into the interior of the wellhead housing as the slip bowl is lowered therein. The seal assembly includes spreaders which are forced inwardly as the seal assembly is moved within the housing and this movement of the spreaders compresses the seal ring so that it is moved radially into sealing engagement between the interior of the wellhead housing and the exterior of the pipe string.
U.S. Pat. Nos. 2,824,757 and 3,287,035 are other structures for supporting and sealing a pipe string within a wellhead housing in which the slip bowl is connected to the seal loading so that the seal is set responsive to loading of the slip bowl by its support through its slips of the pipe string.